Magnetic order of the disturbed spin-Peierls compound (Cu,Mg)GeO3

We have measured muon spin relaxation (mu SR) in (Cu1-xMgx)GeO3, a spin-Pei erls compound disturbed by the Mg (S = 0) doping of the Cu (S = 1/2) spin c hain. Static magnetic order was observed in the zero-field mu SR measuremen ts below the Neel temperatures determined by the susceptibility measurement s. The zero-field muon relaxation exhibits a characteristic line shape in d isturbed spin-Peierls compounds; muon spin precession together with exponen tial static relaxation. The amplitude of the precession, which is a measure of spacial homogeneity of the ordered moment size, takes the maximum at Mg concentration x similar to 0.03, which is just above the phase boundary in the temperature-Mg concentration (T-x) phase diagram. (C) 2000 Elsevier Sc ience B.V. All rights reserved.